The present invention relates to magnetic target devices and in particular to a novel magnetic mechanism for resetting a magnetic target device without requiring the energization of an electrical reset circuit.
It is known to provide electrical equipment with an indicator device having a magnetically actuatable target which displays a desired bit of information when an electrical "Set" pulse of current is caused to flow through a target coil of the indicator device, such as described in U.S. Pat. No. 3,140,553, issued July 14, 1964 to Taylor. The target information is magnetically held to alert an operator to the need for some act of intervention. The target of the indicator device is reset by the operator when that intervention has occurred. The previous method for resetting a magnetic target was by passing an electrical "Reset" pulse of current through the target coil in the opposite direction from the "Set" pulse, as is described in U.S. Pat. No. 3,735,215, issued May 22, 1973, and U.S. Pat. No. 3,599,045, issued Oct. 3, 1969, both to the assignee of the present invention.
In none of the above patents is it possible to produce a pulse of current through the target coil in the reset direction when the equipment is shut down and voltage is not available.